Progress in the development of an adenovirus 26 vector platform for HIV vaccines

Evaluation of: Baden LR, Walsh SR, Seaman MS et al. First-in-human evaluation of the safety and immunogenicity of a recombinant adenovirus serotype 26 HIV-1 Env Vaccine (IPCAVD 001). J. Infect. Dis. 207(2), 240-247 (2013). A novel replication-deficient recombinant adenovirus serotype 26 vector expressing the envelope protein of a clade A HIV type 1 was evaluated in a group of 60 healthy human volunteers. Three different doses of the recombinant adenovirus vector were used to assess its safety and immunogenicity. The vaccine was found to be generally safe, with no vaccine-related serious adverse events. Although all vaccinated subjects developed neutralizing antibodies against the adenovirus 26 vector, these antibodies did not interfere with the boosting of immune responses against the expressed HIV envelope protein. HIV envelope-specific binding antibodies as well as cellular immune responses were detected in the majority of individuals, persisting for at least 1 year. These results are discussed in the context of previously published protection data in nonhuman primates and of recently published immunological findings with this new vector. Options to proceed to vaccine efficacy trials with this vaccine are reviewed.